GNAT - System.ads - System Implementation Parameters

[Hibou57 <yannick_duchene@yahoo.fr>]

Hola, Hello, Salam lik,

In the GNAT standard librarie source code, one may see in the "System"
package specification (system.ads), a section commented as "System
Implementation Parameters".

Here is what it contains :

>   --------------------------------------
>   -- System Implementation Parameters --
>   --------------------------------------
>
>   --  These parameters provide information about the target that is used
>   --  by the compiler. They are in the private part of System, where they
>   --  can be accessed using the special circuitry in the Targparm unit
>   --  whose source should be consulted for more detailed descriptions
>   --  of the individual switch values.
>
>   AAMP                      : constant Boolean := False;
>   Backend_Divide_Checks     : constant Boolean := False;
>   Backend_Overflow_Checks   : constant Boolean := False;
>   Command_Line_Args         : constant Boolean := True;
>   Configurable_Run_Time     : constant Boolean := True;
>   Denorm                    : constant Boolean := True;
>   Duration_32_Bits          : constant Boolean := False;
>   Exit_Status_Supported     : constant Boolean := True;
>   Fractional_Fixed_Ops      : constant Boolean := False;
>   Frontend_Layout           : constant Boolean := False;
>   Functions_Return_By_DSP   : constant Boolean := False;
>   Machine_Overflows         : constant Boolean := False;
>   Machine_Rounds            : constant Boolean := True;
>   OpenVMS                   : constant Boolean := False;
>   Signed_Zeros              : constant Boolean := True;
>   Stack_Check_Default       : constant Boolean := False;
>   Stack_Check_Probes        : constant Boolean := False;
>   Support_64_Bit_Divides    : constant Boolean := True;
>   Support_Aggregates        : constant Boolean := True;
>   Support_Composite_Assign  : constant Boolean := True;
>   Support_Composite_Compare : constant Boolean := True;
>   Support_Long_Shifts       : constant Boolean := True;
>   Suppress_Standard_Library : constant Boolean := True;
>   Use_Ada_Main_Program_Name : constant Boolean := False;
>   ZCX_By_Default            : constant Boolean := False;
>   GCC_ZCX_Support           : constant Boolean := False;
>   Front_End_ZCX_Support     : constant Boolean := False;

Unfortinately, I was not able to found any formal documentation about
the meaning of each of this parameter. I may guess some meanings, but
I do not want to guess, I rather want to be sure.

I've found one the web some mailing list where people try to guess and
play with it, but without beeing sure of anything (not better than
me). By the way, there seems to be some interesting project of OS
kernels written in Ada ;) Good! (good idea to use Ada for this kind of
stuff... certainly better than C).

I would like, if some people know, to have some suggestions to get
formal documentations about those parameters.

I think this may be an interresting subject, not solely for me ;)

Thanks to all boys and girls around here :)

Read you soon...

Yannick